Aspects of this disclosure include many systems, subsystems, components and subcomponents. Background details already known are not repeated herein. Such background information may include information contained in the following materials:                U.S. Pat. No. 8,229,075 to Cowan et al., titled “Targets and Processes for Fabricating Same,” issued Jul. 24, 2012;        U.S. Pat. No. 8,389,954 to Zigler et al., titled “System for Fast Ions Generation and a Method Thereof,” issued Mar. 5, 2013;        U.S. Pat. No. 8,530,852 to Le Galloudec, titled “Micro-Cone Targets for Producing High Energy and Low Divergence Particle Beams,” issued Sep. 10, 2013;        U.S. Pat. No. 8,750,459 to Cowan et al., titled “Targets and Processes for Fabricating Same,” issued Jun. 10, 2014;        U.S. Pat. No. 9,236,215 to Zigler et al., titled “System for Fast Ions Generation and a Method Thereof,” issued Jan. 12, 2016;        U.S. Pat. No. 9,345,119 to Adams et al., titled “Targets and Processes for Fabricating Same,” issued May 17, 2016; and        U.S. Pat. No. 9,530,605 to Nahum et al., titled “Laser Activated Magnetic Field Manipulation of Laser Driven Ion Beams,” issued Dec. 27, 2016.        
Particle radio-therapy conducted with ions may be used to treat disease. In one form of particle therapy, called proton therapy, a tumor is treated by irradiating it with protons (e.g., hydrogen ions). Proton therapy has advantages over conventional photon-based therapies (e.g., x-ray and gamma ray therapies) in part due to the way protons and photons interact with a patient's tissue.
FIG. 1 shows the radiation dose as a function of tissue depth for both photon and proton therapies. Before a particle can irradiate the treatment volume 106 defined by the patient's treatment plan, it typically must traverse the patient's skin and other healthy tissue before reaching the treatment volume 106 of the patient. In doing so, the particles can damage healthy tissue, an undesirable side-effect of the treatment. As shown in curve 102 of FIG. 1, photons (e.g., x-rays) deliver most of their energy to the regions near the patient's skin. For tumors deeper in the patient's body, this interaction may damage healthy tissue. Additionally, some photons traverse the patient's body beyond the treatment volume 106, irradiating yet more healthy tissue behind the tumor before ultimately exiting the other side of the patient's body. Although the radiation doses to these other healthy tissues is lower than the dose delivered near the patient's skin, it is still undesirable.
Unlike photons, protons, exhibit a very desirable interaction with the patient's tissue. As shown by curve 104 in FIG. 1, the peak interaction of protons with the patient's tissue occurs deeper within the patient and may cease abruptly after the peak interaction. Additionally, protons interact with surface tissues much less than photons, meaning that the majority of the proton beam's energy can be delivered to the treatment volume 106, and the irradiation of healthy tissue can be reduced. Taking advantage of these benefits, proton therapy thus allows more precise administration of energy to unhealthy tissue in patients while avoiding damage to healthy tissue. For example, proton therapy may reduce damage to surrounding healthy tissue by 2 to 6 times when compared to x-ray therapy, thereby improving patient survival and quality of life. Protons may reduce the lifetime risk of secondary cancer in children by 97%, compared to x-rays.
Commercial proton therapy centers are currently rare due to disadvantages in existing proton therapy systems, which generate proton beams by using large and costly particle accelerators. Accelerator-based systems can be massive and are not scalable. As an example, FIG. 2 shows an approximate size comparison of an accelerator-based proton therapy system against a football field. The energy requirements and maintenance costs inherent in operating an accelerator-based system are also immense. Taken together, these disadvantages lead to exorbitant construction and maintenance costs associated with proton therapy. In addition to the extravagant costs associated with accelerator-based proton beam generation, adjusting certain properties of the proton beam (e.g., the beam energy and beam flux) can be cumbersome and time-consuming in such systems. This leads to longer treatment times and low patient throughput, further increasing the cost of individual treatments as fewer patients share the cost burden. Accordingly, few proton therapy centers currently exist, and patients often receive inferior treatments due, in part, to unavailability of proton therapy.
The present disclosure is directed to alternative approaches to proton therapy. Although the embodiments disclosed herein contemplate the medical application of proton beam therapy, a person of ordinary skill in the art would understand that the novel proton beam generating methods and systems described below can be used in any application where a proton beam is desired.